نشریه نوآوری در علوم و فناوری غذایی
پیاپی 18 (زمستان 1392)

The main purpose of this research was to conjugate concentrated whey protein 80% (WPC) with dextran under Maillard reaction conditions, to investigate the functional properties of the resulting conjugate. Conjugation was carried at different temperatures, different ratios of dextran: whey protein for different length of time. The covalent attachment of dextran to whey protein was confirmed by SDS-PAGE and gel filtration chromatography. The best condition was incubation at of 60oC for 10 days and at a 1:5 whey protein to dextran. The whey protein-dextran conjugate exhibited improved solubility at pH's 3, 5, 7, 9 and at different temperatures 25, 40, and 60oC), increased heat stability, with better emulsion activity and emulsion stability compared with control samples (no heating, no dextran) and the samples heated in the absence of dextran.

In this study, the antimicrobial activities including minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of oreganum water extract (OWE) and nettle water extract (NWE) were evaluated against 3 foodborne pathogenic and spoilage bacteria including Escherichia coli(E), Salmonella typhi(S) and Pseudomonas aeruginosa(Ps). The MICs of OWE against S were observed 1.25 mg/ml, and against Ps and E were observed 5 mg/ml. The MICs of NWE against S, Ps and E were observed 1.25 5, 2.5 mg/ml respectively. The MBC of OWE against S, Ps and E was 1.25,10 and 10 mg/ml respectively. The MBC of NWE against S, Ps and E was 2.5, 10 and 20 respectively.

In fluidized bed dryer, high velocity of air causes wastage of thermal energy. In order that fixed bed dryer be combined with fluidized bed dryer, it was mounted after fluidized bed in air way. According to the first law of thermodynamic, energy and effective parameters on energy consume were analyzed. Experiments were performed at three temperature ranges of, 60 and 70°C, three bed depths of 4, 6 and 8cm for the lower bed and two bed depths of 6 and 8 cm for the higher. Increasing bed depth of each bed showed clear effects on EU and EUR of the other floor. The EU value of top floor was more than that of bottom floor. Maximum energy consumption was obtained in 70 °C at 8dw-8up bed depth and energy consumption ratio was obtained in 50 °C at 8dw-8up.

In this project, the quantitative and qualitative characteristics of malts (hot water extract, cold water extract, diastatic power, total and soluble protein, nitrogen modification index, colour and β-glucanase activity) obtained from cereals of barley var. Sahra, wheat variety Tajan and Triticale were investigated in Completely Randomized Design (CRD) with replications. The results showed that protein content of malts from barley and wheat was 15.2 and 14.4 higher than that of triticale, respectively. Meanwhile, the colbach index of malt from triticale was 19.3 and 29.0% higher than that of malts from barley and wheat, respectively. A negative linear correlation was observed between total protein content and colbach index (R2, 0.94). Hot and cold water extract of triticale malt was higher than that of wheat and barley malt. Triticale and wheat have a maximum and minimum of, respectively. The maximum (716 U/Kg) and minimum (97 U/Kg) of β-glucanase activity were due to triticale and wheat malts, respectively. The color of extracts obtained from all investigated malts was in the range of 1.82 to 2.51.

Due to obesity disorders and related diseases, low calorie soft drinks have been greatly favored in recent years. In this study, all the sugar in the reference syrup was eliminated to produce diet syrups. Pectin as a bulking agent and aspartame and acesulfame-k as sweeteners substitute for sucrose were applied. For studying the selected formulations during storage, these syrups were stored at room temperature and 40 °C for 4 months. Degradation of aspartame was measured using HPLC method and then its degradation kinetics was determined. Results showed that time and temperature had significant effects (p<0.001) on the aspartame stability but the type of formulation (different types of syrups) had no significant effects. The first order reaction rate was applied for calculating the constant rates of aspartame degradation. The calculated reaction rate constants for the diet syrups were about 0.1 at ambient temperature and about 0.3 at 40 °C. The half-life of the aspartame degradation was about 4 months at ambient temperature and about 2 months at 40 °C. Therefore, the amount of aspartame in the product depends on temperature, time and environmental conditions. Acceptability of aspartame decreases at high temperatures due to the degradation of aspartame, so it is not suggested to be used in sour cherry syrup in these conditions. But, it can be easily used in sour cherry syrup at around ambient temperatures.

In recent years, reducing the fat content and production of dietetic ice cream has been taken in consideration. However, reducing the amount of fat in ice cream products, can negatively affect product acceptability through making some changes in viscosity and textural attributes. Fat replacers are components that can replace some of the fat in the food served. At the same time due to lower calorie content it can lead to a decrease in the production of energy by food products. In this research, the effect of a protein based (milk protein concentrate) and a carbohydrate-based (inulin) fat replacer in three levels (0, 2 and 4%) on the rheological and textural properties of low fat (5% fat) ice cream was investigated. All the mixtures showed pseudoplastic flow behaviour and the apparent viscosity decreased with increasing shear rate. Using mpc led to increasing consistency coefficient and decreasing flow behavior index of ice cream mixtures while no significant differences was observed between mixtures containing inulin in the case of these two parameters. Apparent viscosity values increased with increasing the amount of mpc and inulin. Also viscosity values for the mixtures containing mpc were higher than those with inulin. No significant difference was obtained for ice cream samples containing inulin in the case of hardness and the highest amount of hardness was associated to the samples with mpc. Ice cream containing 4% inulin had the highest amount of adhesiveness and no significant difference was detected between other samples.

Kefiran is a microbial exopolysaccharide (EPS) which is produced by acid lactic bacteria and fungi during their growth. In this study, kefir grain cultivation and its kefiran extraction was carried out, respectively. Kefiran was added at the rate of 1%, 2% and 3% (w/w flour basis) to the dough and its effects on the quality properties and shelf life of bulky bread was evaluated using a completely randomized design with four treatments of kefiran (control, 1%, 2% and 3%) and in triplicates. The staling, shelf life and volume of bread were analyzed by Instron texture analyzer machine, Incubator and rapeseed displacement method, respectively. Analysis of variance and the Duncan’s multiple range test were used by SPSS Software (v.16.00 INC, USA) to analyze the data (P < 0.05). The results for dye to physicochemical properties of wheat and its flour showed that wheat had high hectoliter weight, water absorption, flour yield and falling number and in contrast, low hectoliter weight, hardness, thousand seed weight, gluten, moisture, protein, zeleny index and SDS-Sedimentation height. The results of staling tests done in three times, 24, 48 and 72 hours showed that addition of kefiran (1%, 2%, 3%) on dough, decreased significantly (p<0.05) the rate of breads crumb staling. Also, breads containing kefiran had lower rate of staling compared to control samples, as bread sample containing 3% kefiran and control sample had the least and the most staling rate respectively. The results of technological properties showed that increase of kefiran levels led to significantly (p<0.05) decrease of breads cooking loss in comparison with control samples. Addition of kefiran (1%, 2% and 3%) caused a significant (p<0.05) increase and decrease in breads volume and specific volume, respectively. The results of sensory evaluation of bread samples showed from a quality point of view, the desirable level of kefiran was 3%. The addition of kefiran increased the shelf life of the breads and extended the shelf life of the bread 3% to 8 days compared with control sample. Based on the results, application of kefiran is recommended in bakery industry to increase quality and shelf life of bulk bread.

In this research, some physical and mechanical properties of Persimmon fruits were measured at moisture content of 44.46 % w.b. The physical properties were length, width, thickness, arithmetic mean diameter, geometric mean diameter, equivalent diameter, spherecity, aspect ratio, mass, surface area, and volume with average magnitudes of 56.01±4.80mm, 54.19±4.84mm, 36.72±2.74mm, 48.07±3.76mm, 48.95±3.92mm, 48.70±3.89mm, 0.8590±0.02, 0.6548±0.03, 72.99±11.34 gr, 72.80±18.41 mm2, 59.18±13.68 mm3 respectively. Knowledge about the frictional force on different surfaces is important in designing equipments and processes. Friction is impressive on the amount of required power for transporting the materials. The values of static coefficient of friction on three surfaces of glass, galvanized iron and plywood were 0.35±0.03, 0.37±0.02 and 0.35±0.03 respectively. Results showed a significant difference between static coefficient of friction on wood and galvanized iron with glass (P = 0.05). Color characteristics were calculated by MATLAB software. Color values L*, a*, b* were 33.29 to 37.75, 6.23 to 9.28 and 9.55 to 11.86 respectively. Persimmon fruit mechanical tests were performed to determine the fracture resistance properties. Mechanical properties were measured with pressure test (pseudo-static) via a universal testing machine. These properties consisted of yield strength, deformation, stiffness and fracture energy with the average values of 18.57±2.45, 5.59±0.46, 10.57±1.17, 52.13±9.73 respectively.

Cantaloupe pastille is a novel as well as healthy fruity product, also it involves suitable processing techniques for decreasing its wastage. Texture perception is an important factor in consumer sensory acceptance also according to international standards, texture is a sensory attribute that must be evaluated by sensory assessors but in industry it is measured by texture analyzers. This study was done being informed from relationships between sensory perception and objective values of cantaloupe pastille textural parameters. Results of study for textural properties with response surface showed that hardness, cohesiveness and chewiness increased when pectin concentration was raised but xanthan concentration declined. PC plot of dependent variables illustrated that hardness and chewiness of samples which were scored by sensory assessors had closely relationships with the same when they were measured by texture analyzers. Also it was observed that there was a reversive relationship among hardness, rubber and chewiness with adhesiveness. It means when values of hardness, rubber, chewiness and cohesiveness increase also cantaloupe pastille acceptance score enhances but value of adhesiveness decreases.

In order to improve the properties of the starch biodegradable films, three components were manipulated: citric acid, carboxy methyl cellulose (CMC) and nanoclay, and the effect of each of these ingredients on the morphological properties and roughness values of the films, as well as their homogeneity were investigated. Afterwards, the effect of nanoclay concentration on the moisture permeability of these films was investigated. AFM results indicated that the starch – CMC biocomposites and starch – CMC – nanoclay bionanocomposites had the lowest and highest roughness values, respectively. Results of the moisture adsorption test indicated that by increasing the nanoclay contents, moisture absorption of the films decreased. The films containing 7% nanoclay showed the lowest moisture absorption value (14.78%). However, according to the results of contact angle test, surface hydrophobisity of the films decreased by an increase in nanoclay contents.

Chickpea (Cicer arietinum L.) seeds are important sources of food proteins. Apart from their nutritional properties, pulse proteins also possess functional properties that play an important role in food formulation and processing. In the present study, the effect of protein extraction pH from kabuli chick pea seeds on solubility, emulsion properties, water absorption capacity and variety nitrogen fractions of isolates were obtained from two extraction methods including alkaline extraction and acidic extraction. In this research, the protein was extracted at pH=2.5 and pH=9.5 and after that the protein was precipitated at Isoelectric point (pH =4.5). All experiments were performed in triplicates and Duncan multiple range test with a confidence interval of 95% was used to compare the means. Protein solubility was studied at pH 2.5 7.0. Environment pH had significant effect on solubility (p≤0.05). The solubility-pH profile of different protein isolates showed minimum solubility in the pH 4.0 and 5.0 and maximum solubility at pH 7 and afterward at pH 2.5, also protein isolates obtained by acidic method (isolate A) had higher solubility than protein isolates obtained by alkaline method (Isolate B). Both two isolates had suitable emulsion properties and water hold capacity. Isolate obtained by acidic method higher emulsification while alkaline method enhanced water absorption capacity (p≤0.05). Electrophoresis of the various fractions revealed that chickpea globulin was made up of sub-units of different molecular weights ranging from 10 to 150 kDa. bands corresponding to molecular weights of 30-40 kDa, which should be attributed to the acidic subunits of the 11S globulin (legumin), while the bands at about 25 kDa probably corresponded to the basic legumin subunit. Bands density of isolate B were thicker, this phenomena could be attributed to nearby of pH utilization for protein extraction at optimum pH of globulin extraction. According to suitable functional properties of chick pea protein isolate, it could be used as a novel protein source substitution in food productions.

In this study, survival of Bifidobacterium lactis (LAFTI-B94) was investigated in both free and microencapsulated forms and its effect on physicochemical, sensory and rheological properties of Doogh was screened during 60 days at 5±1°C cold room. Treatments involved C (control, no probiotic), B and BC containing Bifidobacterium lactis in free and microencapsulated form respectively. The analysis of the results showed that the number of Bifidobacterium lactis counts decreased in free form 0.26 log and increased in capsulated form 0.36 log. The results also indicated that both free and microencapsulated form were efficient enough to keep the number of probiotic bacteria above the threshold level for minimum therapeutic 107 CFU g-1 of Doogh but the number of bacteria added in microencapsulated form was higher than that of the free form of bacteria. The analysis of the results showed that amount of moisture, acidity, pH content, stability and viscosity were significantly different between samples of doogh (P <0.01). The probiotics bacterial improved viscosity and stability of Doogh that encapsulated forms showed to have higher stability (46.25%) and viscosity (54.13 cP) than those of free forms. According to the results of sensory evaluations, significant difference was observed between the samples from a flavor point of view. Doogh samples containing Bifidobacterium lactis respectively gained higher scores for flavor in comparison with other samples (P<0.05). So probiotics not only did not adversely affect physicochemical and sensory properties, but also improved the stability and rheological properties and flavor of Doogh; Therefore, Doogh can be an effective medium for delivering probiotic organisms.